I m actually an android developper in a little society in France. I ve never been faced to this problem before now.
Explanation :
We have developped an android application which has to work with and without network connection (impliying synchronization ascending and descending)
The user has to connect himself, then we request the WebService to access the informations he needs to make his treatments. But, he needs to get ~2500 lines (marshalled by JackSon in our objects). This synchronization takes nearly 3 mns in 3g and more than 5 mns in Edge... and then make what he had to do, and sent the information back to the server when he get a network connection.
MySQL and our webservices give information in good time ( ~0.05s/requests for mysql, and ~105ms/request accessing the webservice from a webpage). We actually need 10-15 requests to get all the needed informations.
Is there any way to reduce, or a solution to improve / refactor our coding methods.
In fact, I guess we didnt think the application by the good side, when I look Google drive mobile or messenger Facebook app which are really really fast x__x' .
So I m looking for a solution, and moreover, we have a client that needs to get ~50 000 lines per users in the next few monthes...
Thanks for all,
Related
Ok so to explain I have server in Java that receives data from a C++ program that I have no control over. So the data is transferred over TCP/IP and the Java server just receives it. The volume of incoming data is huge and it comes at a very fast rate, just imagine a terminal printing loads of lines really fast.. I don't need to get all of it, just as much as I can would be great..
Now I need to send that data to an android device and display it.
I have no idea what is the best approach to so this.
I am currently pinging the server from my android device every 50ms using an executor. Then I use a handler to display the data. I have already posted a question with code here: related question.
Obviously the android app will need to ping it while the app is running so I can't avoid the while(true) scenario.
I have read about 100000000 ways to do concurrency in Android, and I do not know what to choose for this.
I tried simple Threads, they were to hard to manage.
I am now running a ExecutorService
I also read about ScheduledExecutorService, but they need a time
duration right ? My app can be running for 5 hours or 5 minutes or 5
years.
I read about HandlerThreads too, but I am not sure they are ideal for
this scenario.
Any help would be great.
I have a domain that is user posts based. I plan to create a user posts based app like 9gag. I need the app to be able to communicate and fetch data hosted from my domain.
Things I need the app to do:
1) Allow users to post pictures though the app.
2)Allow users to leave comments through the app.
3)Allow users to leave 'likes' though the app.
I want the data to be stored on my domain, while when a user opens the app, the app will fetch this data from the domain and display it for the user. How can I make my app communicate with the domain?
Thanks!
The best way to do this would be to implement an API on your domain that your app can send requests to. I cannot explain all this in detail here because it would require a lot of space and a full blown tutorial, but I can tell you what to research and what to implement to make this happen.
First off you need to create an API for your app to send requests to. I suggest a "RESTful" api as they are pretty strait forward to the average programmer. Here is a good video that explains what an API is and a little bit of how they are typically implemented. https://youtu.be/7YcW25PHnAA
After you have an API setup, you have "encode" the information so that it is easy to parse once your app has a hold of all that information. To do this we use a "data-interchange format". One of the big ones being used today is JSON, see their website to learn more here: http://www.json.org/ JSON is pretty strait forward and easy to understand if you have a concept of what Programming: objects, strings, arrays etc are.
Ok so you have gotten your information from the server, you have parsed it from the JSON you got, and displayed all your content... now, what do you do if your user give a thumbs up or comment on something? This is also implemented via the API, this part should be easiest for you, it involves wrapping up the required data (Content id, user id, what they did [ie liked the content]) and send this via a http request, just like how you got your information in the first place, but instead of reading the data response, now we are just sending the HTTP request from the app, and we don't care what happens next (on the app level) its up to the server to record the data from the HTTP request.
I would highly suggest looking up how to create API and look through some tutorials... there are a lot of tutorials out there that want you to modify the HTACCESS file on the server, this is really necessary (Boy I hope I don't get crucified for saying that; fellow Stack Overflow Citizens, if you disagree, please explain your reasoning) Obviously for a large mainstream website, the whole HTACCESS file might be a good idea, but for a beginner, I don't think it is really needed.
I searched in google and stackoverflow for my problem, but couldn't find a good solution. Below is the description,
Our Java web application displays search results from our local database and external webservice API calls. So, the search logic should combine these results and display it in the result page. The problem is, the external API calls return the results slower than our local DB calls. Performance is crucial for our search results and the results should be live i.e. we should not cache or persist the external results in our local DB. Right now, we are spanning two threads, one for the DB call and another one for the exteral API, and combine these results and display it on the screen. But it kills the performance of our application, particularly when we call more than one external APIs.
Is there any architectural solution for this problem?
Any help would be greatly appreciated.
Thanks.
You cannot display data before you have it.
1) You can display your local data and as they come, add via ajax other data.
2) And if there are repeated questions, you could cache external answers for short time (and display them with warning that they are old and that they will be replaced by fresh answer) and as soon as fresh anwer arrive, push new answer.
With at least 1), system will be responsive, with 2) usable answer can be available imediately, even if its not current.
btw, if external source take long to answer, are you sure that their answer is not stale (eg. if they gather some data and wait for rest, then what they gathered so far can go stale)? So maybe (and maybe not) short term persisting is not as bad as you think.
I have some issues with my parts of final year projects. We are implementing a plagiarism detection framework. I'm working on internet sources detection part. Currently my internet search algorithm is completed. But I need to enhance it so that internet search delay is reduced.
My idea is like this:
First user is prompt to insert some web links as the initial knowledge feed for the system.
Then it crawl through internet and expand it's knowledge
Once the knowledge is fetch System don't need to query internet again. Can someone provide me some guidance to implement it? We are using Java. But any abstract detail will surely help me.
if the server side programming is you hand then you can manage a tabel having a boolean in database which shows whether the details were read before. every time your client connects to server, it will check the boolean first and if boolean was set false then it will mean that there is a need to send updates to client other wise no updates will be sent,
the boolean will become true every time when client downloads any data from server and will become false when ever the database is updated
I'm not quite sure that I understand what you're asking. Anyway:
if you're looking for a Java Web crawler, then you I recommend that you read this question
if you're looking for Java libraries to build a knowledge base (KB), then it really depends on (1) what kind of properties your KB should have, and (2) what kind of reasoning capabilities you expect from your KB. One option is to use the Jena framework, but this requires that you're comfortable with Semantic Web formalisms.
Good luck!
I'm trying to implement a Cometd/Bayeux server on Android using iJetty. The Jetty implementation itself works just fine serving static pages along with servlets. I am trying to up the ante a bit and create a Bayeux application on the phone but I'm having some trouble. I can hit the page that has the dojo cometd scripts on it, but I am unable to subscribe to the channel. When I view firebug/chome developer tools, I see a series of posts/gets that last a couple of milliseconds (~14). However, when I run a cometd application on a normal machine, the posts/gets last several seconds (~14 seconds) before timing out and reopening the connection. This second scenario makes sense to me with my understanding of how continuation in HTTP works. So I'm thinking that something is not allowing those connections to hang open and prematurely returning a value and consequently closing the connection. I would post my source but I'm not sure what to post short of posting everything...(it is open source though so if you want to have a look it's at http://webtext-android.googlecode.com).
So my question is, does anybody think that there could be some underlying limitation imposed by the Android system that is preventing these servlets from working? Are there assumptions that are made by the Jetty Bayeux implementation with regards to the underlying system? Or is it more likely that somehow I have a bad implementation of the ContinuationCometdServelt? I should note that all of the posts/gets from the client return 200 OK messages so I'm not inclined to think that the Android system is simply terminating the connection.
I know this is a bit off the wall and I'm definitely trying to do something a bit out of the ordinary but any suggestions or tips would be greatly appreciated.
In case anybody discovers this and has similar problems (this applies to all cometd implementations regardless of host), I discovered that the issue was with using the Google js library. For some reason, the dojo scripts I was loading from Google (1.4) didn't have a valid implementation of cometd. I switched my dojo script to the one that was used by the jetty-1.6.23 example and it works perfectly.